drivers/s390/block/dcssblk.c

   1 /*
   2  * dcssblk.c -- the S/390 block driver for dcss memory
   3  *
   4  * Authors: Carsten Otte, Stefan Weinhuber, Gerald Schaefer
   5  */
   6
   7 #define KMSG_COMPONENT "dcssblk"
   8 #define pr_fmt(fmt) KMSG_COMPONENT ": " fmt
   9
  10 #include <linux/module.h>
  11 #include <linux/moduleparam.h>
  12 #include <linux/ctype.h>
  13 #include <linux/errno.h>
  14 #include <linux/init.h>
  15 #include <linux/slab.h>
  16 #include <linux/blkdev.h>
  17 #include <linux/completion.h>
  18 #include <linux/interrupt.h>
  19 #include <linux/platform_device.h>
  20 #include <linux/pfn_t.h>
  21 #include <asm/extmem.h>
  22 #include <asm/io.h>
  23
  24 #define DCSSBLK_NAME "dcssblk"
  25 #define DCSSBLK_MINORS_PER_DISK 1
  26 #define DCSSBLK_PARM_LEN 400
  27 #define DCSS_BUS_ID_SIZE 20
  28
  29 static int dcssblk_open(struct block_device *bdev, fmode_t mode);
  30 static void dcssblk_release(struct gendisk *disk, fmode_t mode);
  31 static blk_qc_t dcssblk_make_request(struct request_queue *q,
  32                                                 struct bio *bio);
  33 static long dcssblk_direct_access(struct block_device *bdev, sector_t secnum,
  34                          void __pmem **kaddr, pfn_t *pfn);
  35
  36 static char dcssblk_segments[DCSSBLK_PARM_LEN] = "\0";
  37
  38 static int dcssblk_major;
  39 static const struct block_device_operations dcssblk_devops = {
  40         .owner          = THIS_MODULE,
  41         .open           = dcssblk_open,
  42         .release        = dcssblk_release,
  43         .direct_access  = dcssblk_direct_access,
  44 };
  45
  46 struct dcssblk_dev_info {
  47         struct list_head lh;
  48         struct device dev;
  49         char segment_name[DCSS_BUS_ID_SIZE];
  50         atomic_t use_count;
  51         struct gendisk *gd;
  52         unsigned long start;
  53         unsigned long end;
  54         int segment_type;
  55         unsigned char save_pending;
  56         unsigned char is_shared;
  57         struct request_queue *dcssblk_queue;
  58         int num_of_segments;
  59         struct list_head seg_list;
  60 };
  61
  62 struct segment_info {
  63         struct list_head lh;
  64         char segment_name[DCSS_BUS_ID_SIZE];
  65         unsigned long start;
  66         unsigned long end;
  67         int segment_type;
  68 };
  69
  70 static ssize_t dcssblk_add_store(struct device * dev, struct device_attribute *attr, const char * buf,
  71                                   size_t count);
  72 static ssize_t dcssblk_remove_store(struct device * dev, struct device_attribute *attr, const char * buf,
  73                                   size_t count);
  74
  75 static DEVICE_ATTR(add, S_IWUSR, NULL, dcssblk_add_store);
  76 static DEVICE_ATTR(remove, S_IWUSR, NULL, dcssblk_remove_store);
  77
  78 static struct device *dcssblk_root_dev;
  79
  80 static LIST_HEAD(dcssblk_devices);
  81 static struct rw_semaphore dcssblk_devices_sem;
  82
  83 /*
  84  * release function for segment device.
  85  */
  86 static void
  87 dcssblk_release_segment(struct device *dev)
  88 {
  89         struct dcssblk_dev_info *dev_info;
  90         struct segment_info *entry, *temp;
  91
  92         dev_info = container_of(dev, struct dcssblk_dev_info, dev);
  93         list_for_each_entry_safe(entry, temp, &dev_info->seg_list, lh) {
  94                 list_del(&entry->lh);
  95                 kfree(entry);
  96         }
  97         kfree(dev_info);
  98         module_put(THIS_MODULE);
  99 }
 100
 101 /*
 102  * get a minor number. needs to be called with
 103  * down_write(&dcssblk_devices_sem) and the
 104  * device needs to be enqueued before the semaphore is
 105  * freed.
 106  */
 107 static int
 108 dcssblk_assign_free_minor(struct dcssblk_dev_info *dev_info)
 109 {
 110         int minor, found;
 111         struct dcssblk_dev_info *entry;
 112
 113         if (dev_info == NULL)
 114                 return -EINVAL;
 115         for (minor = 0; minor < (1<<MINORBITS); minor++) {
 116                 found = 0;
 117                 // test if minor available
 118                 list_for_each_entry(entry, &dcssblk_devices, lh)
 119                         if (minor == entry->gd->first_minor)
 120                                 found++;
 121                 if (!found) break; // got unused minor
 122         }
 123         if (found)
 124                 return -EBUSY;
 125         dev_info->gd->first_minor = minor;
 126         return 0;
 127 }
 128
 129 /*
 130  * get the struct dcssblk_dev_info from dcssblk_devices
 131  * for the given name.
 132  * down_read(&dcssblk_devices_sem) must be held.
 133  */
 134 static struct dcssblk_dev_info *
 135 dcssblk_get_device_by_name(char *name)
 136 {
 137         struct dcssblk_dev_info *entry;
 138
 139         list_for_each_entry(entry, &dcssblk_devices, lh) {
 140                 if (!strcmp(name, entry->segment_name)) {
 141                         return entry;
 142                 }
 143         }
 144         return NULL;
 145 }
 146
 147 /*
 148  * get the struct segment_info from seg_list
 149  * for the given name.
 150  * down_read(&dcssblk_devices_sem) must be held.
 151  */
 152 static struct segment_info *
 153 dcssblk_get_segment_by_name(char *name)
 154 {
 155         struct dcssblk_dev_info *dev_info;
 156         struct segment_info *entry;
 157
 158         list_for_each_entry(dev_info, &dcssblk_devices, lh) {
 159                 list_for_each_entry(entry, &dev_info->seg_list, lh) {
 160                         if (!strcmp(name, entry->segment_name))
 161                                 return entry;
 162                 }
 163         }
 164         return NULL;
 165 }
 166
 167 /*
 168  * get the highest address of the multi-segment block.
 169  */
 170 static unsigned long
 171 dcssblk_find_highest_addr(struct dcssblk_dev_info *dev_info)
 172 {
 173         unsigned long highest_addr;
 174         struct segment_info *entry;
 175
 176         highest_addr = 0;
 177         list_for_each_entry(entry, &dev_info->seg_list, lh) {
 178                 if (highest_addr < entry->end)
 179                         highest_addr = entry->end;
 180         }
 181         return highest_addr;
 182 }
 183
 184 /*
 185  * get the lowest address of the multi-segment block.
 186  */
 187 static unsigned long
 188 dcssblk_find_lowest_addr(struct dcssblk_dev_info *dev_info)
 189 {
 190         int set_first;
 191         unsigned long lowest_addr;
 192         struct segment_info *entry;
 193
 194         set_first = 0;
 195         lowest_addr = 0;
 196         list_for_each_entry(entry, &dev_info->seg_list, lh) {
 197                 if (set_first == 0) {
 198                         lowest_addr = entry->start;
 199                         set_first = 1;
 200                 } else {
 201                         if (lowest_addr > entry->start)
 202                                 lowest_addr = entry->start;
 203                 }
 204         }
 205         return lowest_addr;
 206 }
 207
 208 /*
 209  * Check continuity of segments.
 210  */
 211 static int
 212 dcssblk_is_continuous(struct dcssblk_dev_info *dev_info)
 213 {
 214         int i, j, rc;
 215         struct segment_info *sort_list, *entry, temp;
 216
 217         if (dev_info->num_of_segments <= 1)
 218                 return 0;
 219
 220         sort_list = kzalloc(
 221                         sizeof(struct segment_info) * dev_info->num_of_segments,
 222                         GFP_KERNEL);
 223         if (sort_list == NULL)
 224                 return -ENOMEM;
 225         i = 0;
 226         list_for_each_entry(entry, &dev_info->seg_list, lh) {
 227                 memcpy(&sort_list[i], entry, sizeof(struct segment_info));
 228                 i++;
 229         }
 230
 231         /* sort segments */
 232         for (i = 0; i < dev_info->num_of_segments; i++)
 233                 for (j = 0; j < dev_info->num_of_segments; j++)
 234                         if (sort_list[j].start > sort_list[i].start) {
 235                                 memcpy(&temp, &sort_list[i],
 236                                         sizeof(struct segment_info));
 237                                 memcpy(&sort_list[i], &sort_list[j],
 238                                         sizeof(struct segment_info));
 239                                 memcpy(&sort_list[j], &temp,
 240                                         sizeof(struct segment_info));
 241                         }
 242
 243         /* check continuity */
 244         for (i = 0; i < dev_info->num_of_segments - 1; i++) {
 245                 if ((sort_list[i].end + 1) != sort_list[i+1].start) {
 246                         pr_err("Adjacent DCSSs %s and %s are not "
 247                                "contiguous\n", sort_list[i].segment_name,
 248                                sort_list[i+1].segment_name);
 249                         rc = -EINVAL;
 250                         goto out;
 251                 }
 252                 /* EN and EW are allowed in a block device */
 253                 if (sort_list[i].segment_type != sort_list[i+1].segment_type) {
 254                         if (!(sort_list[i].segment_type & SEGMENT_EXCLUSIVE) ||
 255                                 (sort_list[i].segment_type == SEG_TYPE_ER) ||
 256                                 !(sort_list[i+1].segment_type &
 257                                 SEGMENT_EXCLUSIVE) ||
 258                                 (sort_list[i+1].segment_type == SEG_TYPE_ER)) {
 259                                 pr_err("DCSS %s and DCSS %s have "
 260                                        "incompatible types\n",
 261                                        sort_list[i].segment_name,
 262                                        sort_list[i+1].segment_name);
 263                                 rc = -EINVAL;
 264                                 goto out;
 265                         }
 266                 }
 267         }
 268         rc = 0;
 269 out:
 270         kfree(sort_list);
 271         return rc;
 272 }
 273
 274 /*
 275  * Load a segment
 276  */
 277 static int
 278 dcssblk_load_segment(char *name, struct segment_info **seg_info)
 279 {
 280         int rc;
 281
 282         /* already loaded? */
 283         down_read(&dcssblk_devices_sem);
 284         *seg_info = dcssblk_get_segment_by_name(name);
 285         up_read(&dcssblk_devices_sem);
 286         if (*seg_info != NULL)
 287                 return -EEXIST;
 288
 289         /* get a struct segment_info */
 290         *seg_info = kzalloc(sizeof(struct segment_info), GFP_KERNEL);
 291         if (*seg_info == NULL)
 292                 return -ENOMEM;
 293
 294         strcpy((*seg_info)->segment_name, name);
 295
 296         /* load the segment */
 297         rc = segment_load(name, SEGMENT_SHARED,
 298                         &(*seg_info)->start, &(*seg_info)->end);
 299         if (rc < 0) {
 300                 segment_warning(rc, (*seg_info)->segment_name);
 301                 kfree(*seg_info);
 302         } else {
 303                 INIT_LIST_HEAD(&(*seg_info)->lh);
 304                 (*seg_info)->segment_type = rc;
 305         }
 306         return rc;
 307 }
 308
 309 /*
 310  * device attribute for switching shared/nonshared (exclusive)
 311  * operation (show + store)
 312  */
 313 static ssize_t
 314 dcssblk_shared_show(struct device *dev, struct device_attribute *attr, char *buf)
 315 {
 316         struct dcssblk_dev_info *dev_info;
 317
 318         dev_info = container_of(dev, struct dcssblk_dev_info, dev);
 319         return sprintf(buf, dev_info->is_shared ? "1\n" : "0\n");
 320 }
 321
 322 static ssize_t
 323 dcssblk_shared_store(struct device *dev, struct device_attribute *attr, const char *inbuf, size_t count)
 324 {
 325         struct dcssblk_dev_info *dev_info;
 326         struct segment_info *entry, *temp;
 327         int rc;
 328
 329         if ((count > 1) && (inbuf[1] != '\n') && (inbuf[1] != '\0'))
 330                 return -EINVAL;
 331         down_write(&dcssblk_devices_sem);
 332         dev_info = container_of(dev, struct dcssblk_dev_info, dev);
 333         if (atomic_read(&dev_info->use_count)) {
 334                 rc = -EBUSY;
 335                 goto out;
 336         }
 337         if (inbuf[0] == '1') {
 338                 /* reload segments in shared mode */
 339                 list_for_each_entry(entry, &dev_info->seg_list, lh) {
 340                         rc = segment_modify_shared(entry->segment_name,
 341                                                 SEGMENT_SHARED);
 342                         if (rc < 0) {
 343                                 BUG_ON(rc == -EINVAL);
 344                                 if (rc != -EAGAIN)
 345                                         goto removeseg;
 346                         }
 347                 }
 348                 dev_info->is_shared = 1;
 349                 switch (dev_info->segment_type) {
 350                 case SEG_TYPE_SR:
 351                 case SEG_TYPE_ER:
 352                 case SEG_TYPE_SC:
 353                         set_disk_ro(dev_info->gd, 1);
 354                 }
 355         } else if (inbuf[0] == '0') {
 356                 /* reload segments in exclusive mode */
 357                 if (dev_info->segment_type == SEG_TYPE_SC) {
 358                         pr_err("DCSS %s is of type SC and cannot be "
 359                                "loaded as exclusive-writable\n",
 360                                dev_info->segment_name);
 361                         rc = -EINVAL;
 362                         goto out;
 363                 }
 364                 list_for_each_entry(entry, &dev_info->seg_list, lh) {
 365                         rc = segment_modify_shared(entry->segment_name,
 366                                                    SEGMENT_EXCLUSIVE);
 367                         if (rc < 0) {
 368                                 BUG_ON(rc == -EINVAL);
 369                                 if (rc != -EAGAIN)
 370                                         goto removeseg;
 371                         }
 372                 }
 373                 dev_info->is_shared = 0;
 374                 set_disk_ro(dev_info->gd, 0);
 375         } else {
 376                 rc = -EINVAL;
 377                 goto out;
 378         }
 379         rc = count;
 380         goto out;
 381
 382 removeseg:
 383         pr_err("DCSS device %s is removed after a failed access mode "
 384                "change\n", dev_info->segment_name);
 385         temp = entry;
 386         list_for_each_entry(entry, &dev_info->seg_list, lh) {
 387                 if (entry != temp)
 388                         segment_unload(entry->segment_name);
 389         }
 390         list_del(&dev_info->lh);
 391
 392         del_gendisk(dev_info->gd);
 393         blk_cleanup_queue(dev_info->dcssblk_queue);
 394         dev_info->gd->queue = NULL;
 395         put_disk(dev_info->gd);
 396         up_write(&dcssblk_devices_sem);
 397
 398         if (device_remove_file_self(dev, attr)) {
 399                 device_unregister(dev);
 400                 put_device(dev);
 401         }
 402         return rc;
 403 out:
 404         up_write(&dcssblk_devices_sem);
 405         return rc;
 406 }
 407 static DEVICE_ATTR(shared, S_IWUSR | S_IRUSR, dcssblk_shared_show,
 408                    dcssblk_shared_store);
 409
 410 /*
 411  * device attribute for save operation on current copy
 412  * of the segment. If the segment is busy, saving will
 413  * become pending until it gets released, which can be
 414  * undone by storing a non-true value to this entry.
 415  * (show + store)
 416  */
 417 static ssize_t
 418 dcssblk_save_show(struct device *dev, struct device_attribute *attr, char *buf)
 419 {
 420         struct dcssblk_dev_info *dev_info;
 421
 422         dev_info = container_of(dev, struct dcssblk_dev_info, dev);
 423         return sprintf(buf, dev_info->save_pending ? "1\n" : "0\n");
 424 }
 425
 426 static ssize_t
 427 dcssblk_save_store(struct device *dev, struct device_attribute *attr, const char *inbuf, size_t count)
 428 {
 429         struct dcssblk_dev_info *dev_info;
 430         struct segment_info *entry;
 431
 432         if ((count > 1) && (inbuf[1] != '\n') && (inbuf[1] != '\0'))
 433                 return -EINVAL;
 434         dev_info = container_of(dev, struct dcssblk_dev_info, dev);
 435
 436         down_write(&dcssblk_devices_sem);
 437         if (inbuf[0] == '1') {
 438                 if (atomic_read(&dev_info->use_count) == 0) {
 439                         // device is idle => we save immediately
 440                         pr_info("All DCSSs that map to device %s are "
 441                                 "saved\n", dev_info->segment_name);
 442                         list_for_each_entry(entry, &dev_info->seg_list, lh) {
 443                                 if (entry->segment_type == SEG_TYPE_EN ||
 444                                     entry->segment_type == SEG_TYPE_SN)
 445                                         pr_warn("DCSS %s is of type SN or EN"
 446                                                 " and cannot be saved\n",
 447                                                 entry->segment_name);
 448                                 else
 449                                         segment_save(entry->segment_name);
 450                         }
 451                 }  else {
 452                         // device is busy => we save it when it becomes
 453                         // idle in dcssblk_release
 454                         pr_info("Device %s is in use, its DCSSs will be "
 455                                 "saved when it becomes idle\n",
 456                                 dev_info->segment_name);
 457                         dev_info->save_pending = 1;
 458                 }
 459         } else if (inbuf[0] == '0') {
 460                 if (dev_info->save_pending) {
 461                         // device is busy & the user wants to undo his save
 462                         // request
 463                         dev_info->save_pending = 0;
 464                         pr_info("A pending save request for device %s "
 465                                 "has been canceled\n",
 466                                 dev_info->segment_name);
 467                 }
 468         } else {
 469                 up_write(&dcssblk_devices_sem);
 470                 return -EINVAL;
 471         }
 472         up_write(&dcssblk_devices_sem);
 473         return count;
 474 }
 475 static DEVICE_ATTR(save, S_IWUSR | S_IRUSR, dcssblk_save_show,
 476                    dcssblk_save_store);
 477
 478 /*
 479  * device attribute for showing all segments in a device
 480  */
 481 static ssize_t
 482 dcssblk_seglist_show(struct device *dev, struct device_attribute *attr,
 483                 char *buf)
 484 {
 485         int i;
 486
 487         struct dcssblk_dev_info *dev_info;
 488         struct segment_info *entry;
 489
 490         down_read(&dcssblk_devices_sem);
 491         dev_info = container_of(dev, struct dcssblk_dev_info, dev);
 492         i = 0;
 493         buf[0] = '\0';
 494         list_for_each_entry(entry, &dev_info->seg_list, lh) {
 495                 strcpy(&buf[i], entry->segment_name);
 496                 i += strlen(entry->segment_name);
 497                 buf[i] = '\n';
 498                 i++;
 499         }
 500         up_read(&dcssblk_devices_sem);
 501         return i;
 502 }
 503 static DEVICE_ATTR(seglist, S_IRUSR, dcssblk_seglist_show, NULL);
 504
 505 static struct attribute *dcssblk_dev_attrs[] = {
 506         &dev_attr_shared.attr,
 507         &dev_attr_save.attr,
 508         &dev_attr_seglist.attr,
 509         NULL,
 510 };
 511 static struct attribute_group dcssblk_dev_attr_group = {
 512         .attrs = dcssblk_dev_attrs,
 513 };
 514 static const struct attribute_group *dcssblk_dev_attr_groups[] = {
 515         &dcssblk_dev_attr_group,
 516         NULL,
 517 };
 518
 519 /*
 520  * device attribute for adding devices
 521  */
 522 static ssize_t
 523 dcssblk_add_store(struct device *dev, struct device_attribute *attr, const char *buf, size_t count)
 524 {
 525         int rc, i, j, num_of_segments;
 526         struct dcssblk_dev_info *dev_info;
 527         struct segment_info *seg_info, *temp;
 528         char *local_buf;
 529         unsigned long seg_byte_size;
 530
 531         dev_info = NULL;
 532         seg_info = NULL;
 533         if (dev != dcssblk_root_dev) {
 534                 rc = -EINVAL;
 535                 goto out_nobuf;
 536         }
 537         if ((count < 1) || (buf[0] == '\0') || (buf[0] == '\n')) {
 538                 rc = -ENAMETOOLONG;
 539                 goto out_nobuf;
 540         }
 541
 542         local_buf = kmalloc(count + 1, GFP_KERNEL);
 543         if (local_buf == NULL) {
 544                 rc = -ENOMEM;
 545                 goto out_nobuf;
 546         }
 547
 548         /*
 549          * parse input
 550          */
 551         num_of_segments = 0;
 552         for (i = 0; (i < count && (buf[i] != '\0') && (buf[i] != '\n')); i++) {
 553                 for (j = i; j < count &&
 554                         (buf[j] != ':') &&
 555                         (buf[j] != '\0') &&
 556                         (buf[j] != '\n'); j++) {
 557                         local_buf[j-i] = toupper(buf[j]);
 558                 }
 559                 local_buf[j-i] = '\0';
 560                 if (((j - i) == 0) || ((j - i) > 8)) {
 561                         rc = -ENAMETOOLONG;
 562                         goto seg_list_del;
 563                 }
 564
 565                 rc = dcssblk_load_segment(local_buf, &seg_info);
 566                 if (rc < 0)
 567                         goto seg_list_del;
 568                 /*
 569                  * get a struct dcssblk_dev_info
 570                  */
 571                 if (num_of_segments == 0) {
 572                         dev_info = kzalloc(sizeof(struct dcssblk_dev_info),
 573                                         GFP_KERNEL);
 574                         if (dev_info == NULL) {
 575                                 rc = -ENOMEM;
 576                                 goto out;
 577                         }
 578                         strcpy(dev_info->segment_name, local_buf);
 579                         dev_info->segment_type = seg_info->segment_type;
 580                         INIT_LIST_HEAD(&dev_info->seg_list);
 581                 }
 582                 list_add_tail(&seg_info->lh, &dev_info->seg_list);
 583                 num_of_segments++;
 584                 i = j;
 585
 586                 if ((buf[j] == '\0') || (buf[j] == '\n'))
 587                         break;
 588         }
 589
 590         /* no trailing colon at the end of the input */
 591         if ((i > 0) && (buf[i-1] == ':')) {
 592                 rc = -ENAMETOOLONG;
 593                 goto seg_list_del;
 594         }
 595         strlcpy(local_buf, buf, i + 1);
 596         dev_info->num_of_segments = num_of_segments;
 597         rc = dcssblk_is_continuous(dev_info);
 598         if (rc < 0)
 599                 goto seg_list_del;
 600
 601         dev_info->start = dcssblk_find_lowest_addr(dev_info);
 602         dev_info->end = dcssblk_find_highest_addr(dev_info);
 603
 604         dev_set_name(&dev_info->dev, "%s", dev_info->segment_name);
 605         dev_info->dev.release = dcssblk_release_segment;
 606         dev_info->dev.groups = dcssblk_dev_attr_groups;
 607         INIT_LIST_HEAD(&dev_info->lh);
 608         dev_info->gd = alloc_disk(DCSSBLK_MINORS_PER_DISK);
 609         if (dev_info->gd == NULL) {
 610                 rc = -ENOMEM;
 611                 goto seg_list_del;
 612         }
 613         dev_info->gd->major = dcssblk_major;
 614         dev_info->gd->fops = &dcssblk_devops;
 615         dev_info->dcssblk_queue = blk_alloc_queue(GFP_KERNEL);
 616         dev_info->gd->queue = dev_info->dcssblk_queue;
 617         dev_info->gd->private_data = dev_info;
 618         dev_info->gd->driverfs_dev = &dev_info->dev;
 619         blk_queue_make_request(dev_info->dcssblk_queue, dcssblk_make_request);
 620         blk_queue_logical_block_size(dev_info->dcssblk_queue, 4096);
 621
 622         seg_byte_size = (dev_info->end - dev_info->start + 1);
 623         set_capacity(dev_info->gd, seg_byte_size >> 9); // size in sectors
 624         pr_info("Loaded %s with total size %lu bytes and capacity %lu "
 625                 "sectors\n", local_buf, seg_byte_size, seg_byte_size >> 9);
 626
 627         dev_info->save_pending = 0;
 628         dev_info->is_shared = 1;
 629         dev_info->dev.parent = dcssblk_root_dev;
 630
 631         /*
 632          *get minor, add to list
 633          */
 634         down_write(&dcssblk_devices_sem);
 635         if (dcssblk_get_segment_by_name(local_buf)) {
 636                 rc = -EEXIST;
 637                 goto release_gd;
 638         }
 639         rc = dcssblk_assign_free_minor(dev_info);
 640         if (rc)
 641                 goto release_gd;
 642         sprintf(dev_info->gd->disk_name, "dcssblk%d",
 643                 dev_info->gd->first_minor);
 644         list_add_tail(&dev_info->lh, &dcssblk_devices);
 645
 646         if (!try_module_get(THIS_MODULE)) {
 647                 rc = -ENODEV;
 648                 goto dev_list_del;
 649         }
 650         /*
 651          * register the device
 652          */
 653         rc = device_register(&dev_info->dev);
 654         if (rc)
 655                 goto put_dev;
 656
 657         get_device(&dev_info->dev);
 658         add_disk(dev_info->gd);
 659
 660         switch (dev_info->segment_type) {
 661                 case SEG_TYPE_SR:
 662                 case SEG_TYPE_ER:
 663                 case SEG_TYPE_SC:
 664                         set_disk_ro(dev_info->gd,1);
 665                         break;
 666                 default:
 667                         set_disk_ro(dev_info->gd,0);
 668                         break;
 669         }
 670         up_write(&dcssblk_devices_sem);
 671         rc = count;
 672         goto out;
 673
 674 put_dev:
 675         list_del(&dev_info->lh);
 676         blk_cleanup_queue(dev_info->dcssblk_queue);
 677         dev_info->gd->queue = NULL;
 678         put_disk(dev_info->gd);
 679         list_for_each_entry(seg_info, &dev_info->seg_list, lh) {
 680                 segment_unload(seg_info->segment_name);
 681         }
 682         put_device(&dev_info->dev);
 683         up_write(&dcssblk_devices_sem);
 684         goto out;
 685 dev_list_del:
 686         list_del(&dev_info->lh);
 687 release_gd:
 688         blk_cleanup_queue(dev_info->dcssblk_queue);
 689         dev_info->gd->queue = NULL;
 690         put_disk(dev_info->gd);
 691         up_write(&dcssblk_devices_sem);
 692 seg_list_del:
 693         if (dev_info == NULL)
 694                 goto out;
 695         list_for_each_entry_safe(seg_info, temp, &dev_info->seg_list, lh) {
 696                 list_del(&seg_info->lh);
 697                 segment_unload(seg_info->segment_name);
 698                 kfree(seg_info);
 699         }
 700         kfree(dev_info);
 701 out:
 702         kfree(local_buf);
 703 out_nobuf:
 704         return rc;
 705 }
 706
 707 /*
 708  * device attribute for removing devices
 709  */
 710 static ssize_t
 711 dcssblk_remove_store(struct device *dev, struct device_attribute *attr, const char *buf, size_t count)
 712 {
 713         struct dcssblk_dev_info *dev_info;
 714         struct segment_info *entry;
 715         int rc, i;
 716         char *local_buf;
 717
 718         if (dev != dcssblk_root_dev) {
 719                 return -EINVAL;
 720         }
 721         local_buf = kmalloc(count + 1, GFP_KERNEL);
 722         if (local_buf == NULL) {
 723                 return -ENOMEM;
 724         }
 725         /*
 726          * parse input
 727          */
 728         for (i = 0; (i < count && (*(buf+i)!='\0') && (*(buf+i)!='\n')); i++) {
 729                 local_buf[i] = toupper(buf[i]);
 730         }
 731         local_buf[i] = '\0';
 732         if ((i == 0) || (i > 8)) {
 733                 rc = -ENAMETOOLONG;
 734                 goto out_buf;
 735         }
 736
 737         down_write(&dcssblk_devices_sem);
 738         dev_info = dcssblk_get_device_by_name(local_buf);
 739         if (dev_info == NULL) {
 740                 up_write(&dcssblk_devices_sem);
 741                 pr_warn("Device %s cannot be removed because it is not a known device\n",
 742                         local_buf);
 743                 rc = -ENODEV;
 744                 goto out_buf;
 745         }
 746         if (atomic_read(&dev_info->use_count) != 0) {
 747                 up_write(&dcssblk_devices_sem);
 748                 pr_warn("Device %s cannot be removed while it is in use\n",
 749                         local_buf);
 750                 rc = -EBUSY;
 751                 goto out_buf;
 752         }
 753
 754         list_del(&dev_info->lh);
 755         del_gendisk(dev_info->gd);
 756         blk_cleanup_queue(dev_info->dcssblk_queue);
 757         dev_info->gd->queue = NULL;
 758         put_disk(dev_info->gd);
 759         device_unregister(&dev_info->dev);
 760
 761         /* unload all related segments */
 762         list_for_each_entry(entry, &dev_info->seg_list, lh)
 763                 segment_unload(entry->segment_name);
 764
 765         put_device(&dev_info->dev);
 766         up_write(&dcssblk_devices_sem);
 767
 768         rc = count;
 769 out_buf:
 770         kfree(local_buf);
 771         return rc;
 772 }
 773
 774 static int
 775 dcssblk_open(struct block_device *bdev, fmode_t mode)
 776 {
 777         struct dcssblk_dev_info *dev_info;
 778         int rc;
 779
 780         dev_info = bdev->bd_disk->private_data;
 781         if (NULL == dev_info) {
 782                 rc = -ENODEV;
 783                 goto out;
 784         }
 785         atomic_inc(&dev_info->use_count);
 786         bdev->bd_block_size = 4096;
 787         rc = 0;
 788 out:
 789         return rc;
 790 }
 791
 792 static void
 793 dcssblk_release(struct gendisk *disk, fmode_t mode)
 794 {
 795         struct dcssblk_dev_info *dev_info = disk->private_data;
 796         struct segment_info *entry;
 797
 798         if (!dev_info) {
 799                 WARN_ON(1);
 800                 return;
 801         }
 802         down_write(&dcssblk_devices_sem);
 803         if (atomic_dec_and_test(&dev_info->use_count)
 804             && (dev_info->save_pending)) {
 805                 pr_info("Device %s has become idle and is being saved "
 806                         "now\n", dev_info->segment_name);
 807                 list_for_each_entry(entry, &dev_info->seg_list, lh) {
 808                         if (entry->segment_type == SEG_TYPE_EN ||
 809                             entry->segment_type == SEG_TYPE_SN)
 810                                 pr_warn("DCSS %s is of type SN or EN and cannot"
 811                                         " be saved\n", entry->segment_name);
 812                         else
 813                                 segment_save(entry->segment_name);
 814                 }
 815                 dev_info->save_pending = 0;
 816         }
 817         up_write(&dcssblk_devices_sem);
 818 }
 819
 820 static blk_qc_t
 821 dcssblk_make_request(struct request_queue *q, struct bio *bio)
 822 {
 823         struct dcssblk_dev_info *dev_info;
 824         struct bio_vec bvec;
 825         struct bvec_iter iter;
 826         unsigned long index;
 827         unsigned long page_addr;
 828         unsigned long source_addr;
 829         unsigned long bytes_done;
 830
 831         blk_queue_split(q, &bio, q->bio_split);
 832
 833         bytes_done = 0;
 834         dev_info = bio->bi_bdev->bd_disk->private_data;
 835         if (dev_info == NULL)
 836                 goto fail;
 837         if ((bio->bi_iter.bi_sector & 7) != 0 ||
 838             (bio->bi_iter.bi_size & 4095) != 0)
 839                 /* Request is not page-aligned. */
 840                 goto fail;
 841         if (bio_end_sector(bio) > get_capacity(bio->bi_bdev->bd_disk)) {
 842                 /* Request beyond end of DCSS segment. */
 843                 goto fail;
 844         }
 845         /* verify data transfer direction */
 846         if (dev_info->is_shared) {
 847                 switch (dev_info->segment_type) {
 848                 case SEG_TYPE_SR:
 849                 case SEG_TYPE_ER:
 850                 case SEG_TYPE_SC:
 851                         /* cannot write to these segments */
 852                         if (bio_data_dir(bio) == WRITE) {
 853                                 pr_warn("Writing to %s failed because it is a read-only device\n",
 854                                         dev_name(&dev_info->dev));
 855                                 goto fail;
 856                         }
 857                 }
 858         }
 859
 860         index = (bio->bi_iter.bi_sector >> 3);
 861         bio_for_each_segment(bvec, bio, iter) {
 862                 page_addr = (unsigned long)
 863                         page_address(bvec.bv_page) + bvec.bv_offset;
 864                 source_addr = dev_info->start + (index<<12) + bytes_done;
 865                 if (unlikely((page_addr & 4095) != 0) || (bvec.bv_len & 4095) != 0)
 866                         // More paranoia.
 867                         goto fail;
 868                 if (bio_data_dir(bio) == READ) {
 869                         memcpy((void*)page_addr, (void*)source_addr,
 870                                 bvec.bv_len);
 871                 } else {
 872                         memcpy((void*)source_addr, (void*)page_addr,
 873                                 bvec.bv_len);
 874                 }
 875                 bytes_done += bvec.bv_len;
 876         }
 877         bio_endio(bio);
 878         return BLK_QC_T_NONE;
 879 fail:
 880         bio_io_error(bio);
 881         return BLK_QC_T_NONE;
 882 }
 883
 884 static long
 885 dcssblk_direct_access (struct block_device *bdev, sector_t secnum,
 886                         void __pmem **kaddr, pfn_t *pfn)
 887 {
 888         struct dcssblk_dev_info *dev_info;
 889         unsigned long offset, dev_sz;
 890
 891         dev_info = bdev->bd_disk->private_data;
 892         if (!dev_info)
 893                 return -ENODEV;
 894         dev_sz = dev_info->end - dev_info->start;
 895         offset = secnum * 512;
 896         *kaddr = (void __pmem *) (dev_info->start + offset);
 897         *pfn = __pfn_to_pfn_t(PFN_DOWN(dev_info->start + offset), PFN_DEV);
 898
 899         return dev_sz - offset;
 900 }
 901
 902 static void
 903 dcssblk_check_params(void)
 904 {
 905         int rc, i, j, k;
 906         char buf[DCSSBLK_PARM_LEN + 1];
 907         struct dcssblk_dev_info *dev_info;
 908
 909         for (i = 0; (i < DCSSBLK_PARM_LEN) && (dcssblk_segments[i] != '\0');
 910              i++) {
 911                 for (j = i; (j < DCSSBLK_PARM_LEN) &&
 912                             (dcssblk_segments[j] != ',')  &&
 913                             (dcssblk_segments[j] != '\0') &&
 914                             (dcssblk_segments[j] != '('); j++)
 915                 {
 916                         buf[j-i] = dcssblk_segments[j];
 917                 }
 918                 buf[j-i] = '\0';
 919                 rc = dcssblk_add_store(dcssblk_root_dev, NULL, buf, j-i);
 920                 if ((rc >= 0) && (dcssblk_segments[j] == '(')) {
 921                         for (k = 0; (buf[k] != ':') && (buf[k] != '\0'); k++)
 922                                 buf[k] = toupper(buf[k]);
 923                         buf[k] = '\0';
 924                         if (!strncmp(&dcssblk_segments[j], "(local)", 7)) {
 925                                 down_read(&dcssblk_devices_sem);
 926                                 dev_info = dcssblk_get_device_by_name(buf);
 927                                 up_read(&dcssblk_devices_sem);
 928                                 if (dev_info)
 929                                         dcssblk_shared_store(&dev_info->dev,
 930                                                              NULL, "0\n", 2);
 931                         }
 932                 }
 933                 while ((dcssblk_segments[j] != ',') &&
 934                        (dcssblk_segments[j] != '\0'))
 935                 {
 936                         j++;
 937                 }
 938                 if (dcssblk_segments[j] == '\0')
 939                         break;
 940                 i = j;
 941         }
 942 }
 943
 944 /*
 945  * Suspend / Resume
 946  */
 947 static int dcssblk_freeze(struct device *dev)
 948 {
 949         struct dcssblk_dev_info *dev_info;
 950         int rc = 0;
 951
 952         list_for_each_entry(dev_info, &dcssblk_devices, lh) {
 953                 switch (dev_info->segment_type) {
 954                         case SEG_TYPE_SR:
 955                         case SEG_TYPE_ER:
 956                         case SEG_TYPE_SC:
 957                                 if (!dev_info->is_shared)
 958                                         rc = -EINVAL;
 959                                 break;
 960                         default:
 961                                 rc = -EINVAL;
 962                                 break;
 963                 }
 964                 if (rc)
 965                         break;
 966         }
 967         if (rc)
 968                 pr_err("Suspending the system failed because DCSS device %s "
 969                        "is writable\n",
 970                        dev_info->segment_name);
 971         return rc;
 972 }
 973
 974 static int dcssblk_restore(struct device *dev)
 975 {
 976         struct dcssblk_dev_info *dev_info;
 977         struct segment_info *entry;
 978         unsigned long start, end;
 979         int rc = 0;
 980
 981         list_for_each_entry(dev_info, &dcssblk_devices, lh) {
 982                 list_for_each_entry(entry, &dev_info->seg_list, lh) {
 983                         segment_unload(entry->segment_name);
 984                         rc = segment_load(entry->segment_name, SEGMENT_SHARED,
 985                                           &start, &end);
 986                         if (rc < 0) {
 987 // TODO in_use check ?
 988                                 segment_warning(rc, entry->segment_name);
 989                                 goto out_panic;
 990                         }
 991                         if (start != entry->start || end != entry->end) {
 992                                 pr_err("The address range of DCSS %s changed "
 993                                        "while the system was suspended\n",
 994                                        entry->segment_name);
 995                                 goto out_panic;
 996                         }
 997                 }
 998         }
 999         return 0;
1000 out_panic:
1001         panic("fatal dcssblk resume error\n");
1002 }
1003
1004 static int dcssblk_thaw(struct device *dev)
1005 {
1006         return 0;
1007 }
1008
1009 static const struct dev_pm_ops dcssblk_pm_ops = {
1010         .freeze         = dcssblk_freeze,
1011         .thaw           = dcssblk_thaw,
1012         .restore        = dcssblk_restore,
1013 };
1014
1015 static struct platform_driver dcssblk_pdrv = {
1016         .driver = {
1017                 .name   = "dcssblk",
1018                 .pm     = &dcssblk_pm_ops,
1019         },
1020 };
1021
1022 static struct platform_device *dcssblk_pdev;
1023
1024
1025 /*
1026  * The init/exit functions.
1027  */
1028 static void __exit
1029 dcssblk_exit(void)
1030 {
1031         platform_device_unregister(dcssblk_pdev);
1032         platform_driver_unregister(&dcssblk_pdrv);
1033         root_device_unregister(dcssblk_root_dev);
1034         unregister_blkdev(dcssblk_major, DCSSBLK_NAME);
1035 }
1036
1037 static int __init
1038 dcssblk_init(void)
1039 {
1040         int rc;
1041
1042         rc = platform_driver_register(&dcssblk_pdrv);
1043         if (rc)
1044                 return rc;
1045
1046         dcssblk_pdev = platform_device_register_simple("dcssblk", -1, NULL,
1047                                                         0);
1048         if (IS_ERR(dcssblk_pdev)) {
1049                 rc = PTR_ERR(dcssblk_pdev);
1050                 goto out_pdrv;
1051         }
1052
1053         dcssblk_root_dev = root_device_register("dcssblk");
1054         if (IS_ERR(dcssblk_root_dev)) {
1055                 rc = PTR_ERR(dcssblk_root_dev);
1056                 goto out_pdev;
1057         }
1058         rc = device_create_file(dcssblk_root_dev, &dev_attr_add);
1059         if (rc)
1060                 goto out_root;
1061         rc = device_create_file(dcssblk_root_dev, &dev_attr_remove);
1062         if (rc)
1063                 goto out_root;
1064         rc = register_blkdev(0, DCSSBLK_NAME);
1065         if (rc < 0)
1066                 goto out_root;
1067         dcssblk_major = rc;
1068         init_rwsem(&dcssblk_devices_sem);
1069
1070         dcssblk_check_params();
1071         return 0;
1072
1073 out_root:
1074         root_device_unregister(dcssblk_root_dev);
1075 out_pdev:
1076         platform_device_unregister(dcssblk_pdev);
1077 out_pdrv:
1078         platform_driver_unregister(&dcssblk_pdrv);
1079         return rc;
1080 }
1081
1082 module_init(dcssblk_init);
1083 module_exit(dcssblk_exit);
1084
1085 module_param_string(segments, dcssblk_segments, DCSSBLK_PARM_LEN, 0444);
1086 MODULE_PARM_DESC(segments, "Name of DCSS segment(s) to be loaded, "
1087                  "comma-separated list, names in each set separated "
1088                  "by commas are separated by colons, each set contains "
1089                  "names of contiguous segments and each name max. 8 chars.\n"
1090                  "Adding \"(local)\" to the end of each set equals echoing 0 "
1091                  "to /sys/devices/dcssblk/<device name>/shared after loading "
1092                  "the contiguous segments - \n"
1093                  "e.g. segments=\"mydcss1,mydcss2:mydcss3,mydcss4(local)\"");
1094
1095 MODULE_LICENSE("GPL");